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Computer Trading and Dark Pools
Bob the Super Hamste writes "CNN Money has an article on computerized trading; specifically, the non-public markets that are often used to execute orders. The company that the article discusses executes 1/8 of all stock trades in the U.S., or about 900 million trades a day. For comparison, the NYSE executes about 700 million trades. The article discusses 'dark pools,' or private markets where quotes aren't disclosed to the broader public markets. If the company is unable to fill an order from within its own dark pool, it will submit the order to the broader public market (13 public exchanges), as well as up to 20 other private dark pools. The quotes offered by the private dark pools, by law, have to be the same or a better quote than those offered on public exchanges. There have been recent questions about whether the quotes provided by dark pools have been the best for customers and there is a current investigation by FINRA into the methods used by market makers and dark pool operators to fill orders."
This isn't really any voodoo here, and it is something stock brokerage companies have been doing for decades or even from the very beginning. If you have two customers where one customer is trying to unload some stock and another is trying to buy the same issue of stock.... why not simply exchange the stock certificates between the two customers without having to go through the big stock exchange?
The point is that these trading companies sometimes have thousands of trades going on all of the time, sometimes with customers having "put" or "stop" orders in place to buy or sell at certain prices. On the whole it really does make the markets much more efficient because the only time you go to the "big boards" is when you have a large number of your customers either all trying to sell or buy a particular stock issue.
This is certainly not something that will "destroy the economy", but rather that it will even help make the "economy" run even better by making sure that those who are either buying or selling shares can get the best possible price among the most number of people who may be interested in either buying or selling that stock. It also keeps stock brokerage costs down, thus lowering your fees for making an individual transaction. In other words, this makes it much easier for "ordinary people" to get involved with the stock market if you really care to do something like that. The New York Stock Exchange was explicitly set up with this kind of arrangement in mind, where people "with a seat" would carry on major transactions on behalf of trading companies, and ordinary people would contract out with those trading companies if you wanted to make occasional trades or buy in low volumes.
That there are problems with brokers and reasons to be concerned about how they are handling your money is something to be concerned about, the mere fact that "dark pools" exist isn't one of those things to panic over. If they didn't exist, all trades would need to happen on the major exchanges and would be a whole lot more expensive with much higher fees. The end result is that it would cause the world economy to collapse if they were outlawed or something else equally stupid. That brokerage houses should be expected to be honest to their customers is what this whole story is about, not the existence of these trading environments.
I worked at a dark pool.
When a whale buys or sells a sizable amount of stock in the public market it moves the price. When they execute the trade it doesn't happen all at once but in blocks. When bids and offers are made other players in the market see it and they try to jump on. This moves the price. The whale would like the price not to move so they can maximize profit. When trades are executed in a dark pool the market doesn't see the trades until they clear at the end of the day. Who trades in a dark pool you might ask? Other whales. Stocks traded in a dark pool are usually fairly distributed between groups of buyers and sellers so no one trading party has an advantage.